A wireless device receives parameters comprising a radio network temporary identifier (RNTI) associated with a multicast and broadcast service (MBS) session; a first scrambling identity associated with the MBS session; and a second scrambling identity associated with unicast transmissions. The wireless device receives, based on the RNTI, a group common downlink control information (DCI) scheduling a transport block (TB) of the MBS session. Based on the group common DCI being received based on the RNTI, the wireless device determines a scrambling identity for the TB being equal to the first scrambling identity, and receives the TB being scrambled with a scrambling sequence initialized by the determined scrambling identity and the RNTI.